Question 1029764: I am helping my daughter in math and she need help with a qustion where she needs to find the range, variance, and the standard deviation for the sets of data.
A) The ages of people at a family reunion.
2,3,7,10,16,17,39,42,44,45,49,50,51,56,70, 77
B) Number of tracks in CDs
8,10,11,11,11,12,13,13,14,15,16
I myself have no idea how to help her and she does not have a text book for me too look off of any hlep is appreciated.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! 2,3,7,10,16,17,39,42,44,45,49,50,51,56,70, 77
Easier to use a calculator for these, but range is the easiest: high minus low or 75
variance is the squared difference between each value and the mean divided by where n is the number of observations, or 16
The standard deviation is the square root of the variance.
on a TI-83, use STAT then LIST, enter the numbers then STAT then CALC, and do 1-variable stats
what you need is
variance: which it doesn't give you. BUT, you have sigma, the o-shaped thing at the bottom of the list, which is the standard deviation: it is 23.103. That is enough decimal places.
The variance is the square of that or 533.73
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number of tracks in CDs.
standard deviation is 2.208
variance is 4.876
range is 8.
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Doing by hand is tedious except for mean.
You have to take the difference of each from mean, square it and add all the squared differences.
With sample data, we typically divide by n-1 or 1 less than the number of observations. With populations, we divide by the number. Write on the paper you treated this as a population. If there is an issue, google variance and you will see that as the primary definition.
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